Conventionally, a resin-made medical container such as a vial has generally been molded by blow molding. However, since the blow molding is a molding method that does not use an inner mold, there has been a problem that the wall thickness of the container is liable to be uneven and the dimensional reproducibility is low.
A method of molding the medical container by injection molding has been known as a measure for solving the problem. Since the injection molding is a molding method that uses an inner mold and an outer mold, there is an advantageous point that it is easy to make the wall thickness of the container even and thus the dimensional reproducibility is high. However, die cutting of the inner mold cannot be conducted in the case of a container such as a vial in which the diameter on the opening side is smaller than the diameter on the body side, and molding the medical container cannot be conducted by the injection molding without some improvement. Thus, a method in which an upper member and a lower member each having a structure obtained by vertically dividing a container are separately injection-molded and thereafter the upper member and the lower member are integrally bound has been proposed.
For example, a method for producing a plastic bottle in which a bottomed tubular main body and a tubular head having a shoulder and a neck are separately molded with a metal mold, and the resultant main body-molded article and a head-molded article are joined with an organic solvent or by ultrasonic has been proposed in Japanese Patent Laid-Open No. 2002-029538.
Moreover, a method for molding a synthetic resin container, in which, when molding a container having different diameters at a body and a mouth, a bottomed tubular body member and a mouth member having a shoulder are separately injection-molded, the lower end of the mouth member is joined to the upper end of the body opening in such a manner that both ends are fitted, and a molten resin is injected in a ring shape along the fitted shoulder to conduct seal molding has been proposed in Japanese Patent Laid-Open No. 52-101180.
Further, as a method for producing a resin-made bottle container in which a tubular neck having a diameter smaller than a diameter of a bottomed tubular body is provided at an upper end of the body, a method for producing a resin-made bottle container, in which an upper side portion and a lower side portion having a shape obtained by vertically dividing the bottle container into two portions at the upper end or the lower end of the body are separately molded with a resin by injection molding, thereafter, in a state where respective divided ends of the upper side portion and the lower side portion are joined, the joined face of the respective parts is shielded from outside, a molten resin is injected by insert molding in a fluid-tight manner, the molten resin is cooled and solidified to make a cover member, and the upper part and the lower part are integrated with the cover member has been proposed in Japanese Patent Laid-Open No. 2004-217311.
Furthermore, as a cosmetic container having a container main body and a lid, a cosmetic container in which the container main body consists of a neck member, a body member, and a connecting member for connecting the two members, a fitting groove for fitting the neck and a body projection protruding from the circumference of the fitting groove are formed at the upper end of the body member, a neck projection is formed in the neck member so as to be adjacent to the body projection when the neck member is fitted to the body member, and the body member and the neck member are welded and fixed with the connecting member formed by a molten resin injected to the upper end of the body member passing through the body projection and the neck projection has been proposed in Japanese Patent Laid-Open No. 2010-280089.